Skip to main content
  1. Home
  2. Space
  3. News

We finally know exactly how long a day on Venus lasts

Georgina Torbet
By
An image of Venus compiled using data from the Mariner 10 spacecraft in 1974
An image of Venus compiled using data from the Mariner 10 spacecraft in 1974 NASA/JPL-Caltech

As Venus is right next door to Earth, you might assume that we know all about our neighbor in the solar system. But in fact, there’s much we don’t know about this planet, due to factors like the thick layer of sulfuric acid clouds which hide most of its surface. And there are some seemingly basic questions about the planet that we don’t have answers to — including exactly how long a Venusian day is.

Now, researchers from the University of California, Los Angeles finally have an answer to that puzzle, after 15 years of painstaking observations. They used radar to bounce signals off the planet’s surface and were able to work out not only the length of its days but also to learn about the size of its core and the axis at which it is tilted.

Recommended Videos

“Venus is our sister planet, and yet these fundamental properties have remained unknown,” said Jean-Luc Margot, a UCLA professor of Earth, planetary and space sciences who led the research, in a statement.

Related

A day on our sister planet lasts 243.0226 Earth days, which is around two-thirds of an Earth year. Venus rotates extremely slowly, which is why its days last so long, and it also spins in the opposite direction to Earth and most other planets. More than this, the rate at which it rotates actually changes over time, with variation in the length of a day of up to 20 minutes. This has made it difficult to find an accurate figure for the length of its days.

“That probably explains why previous estimates didn’t agree with one another,” Margot said.

The researchers think that Venus’s strange, thick atmosphere might be responsible for this variation. Its atmosphere rotates much faster than the planet does, which might affect the rotation through momentum.

The team also discovered that Venus is tilted by 2.6392 degrees and that its core is around 2,200 miles across, which makes it a similar size to Earth’s core. The researchers made these discoveries by firing radio waves at the planet and watching for when the waves bounced back and the echo could be detected by telescopes on Earth.

“We use Venus as a giant disco ball,” said Margot. “We illuminate it with an extremely powerful flashlight—about 100,000 times brighter than your typical flashlight. And if we track the reflections from the disco ball, we can infer properties about the spin [state].”

The research is published in the journal Nature Astronomy.

Editors' Recommendations

Topics
Georgina Torbet
Georgina Torbet
Space Writer
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
We now know what caused comet ‘Oumuamua’s strange orbit
An artist’s depiction of the interstellar comet ‘Oumuamua, as it warmed up in its approach to the sun and outgassed hydrogen (white mist), which slightly altered its orbit. The comet, which is most likely pancake-shaped, is the first known object other than dust grains to visit our solar system from another star.

Remember what feels like decades ago, when we were visited by a comet from another solar system in 2019? Interstellar comet ‘Oumuamua captured headlines when its cigar-shaped body was spotted following an unusual orbit through our solar system, and subsequent research suggested it might once have been part of a Pluto-like planet and was possibly pancake-shaped.

One thing particularly puzzled astronomers, though, because the comet was accelerating away from the sun in a path that seemed strange. Now, researchers say they have an explanation for its unusual pathway, and it isn't aliens -- it's a natural phenomenon called outgassing.

Read more
Venus’ volcanic activity has left it with a squishy outer shell
This illustration of the large Quetzalpetlatl Corona located in Venus’ southern hemisphere depicts active volcanism and a subduction zone, where the foreground crust plunges into the planet’s interior. A new study suggests coronae reveal locations where active geology is shaping Venus’ surface.

Venus might be our neighbor in the solar system, but there's a lot we still don't know about the planet. That's partly because of its high temperatures and atmospheric pressure which make it difficult to send probes there, and also because its thick atmosphere makes it difficult to observe from orbit. But researchers have recently dug through data from a decades-old NASA mission to learn about the strange geological processes which renew its surface.

One of the open questions about Venus is how it loses its heat, as, unlike Earth, Venus doesn't have tectonic plates. By looking at data from the Magellan mission, researchers discovered that the outer layer of Venus' surface, called the lithosphere, may be considerably thinner than previously thought and could let heat escape from the planet's hot core.

Read more
Two spacecraft worked together to learn about Venus’ magnetic field
Artist impression of BepiColombo flying by Venus on 10 August 2021. The spacecraft makes nine gravity assist maneouvres (one of Earth, two of Venus and six of Mercury) before entering orbit around the innermost planet of the Solar System.

When spacecraft launch to visit distant planets in the solar system, they rarely travel directly from Earth to their target. Because of the orbits of the planets and limitations on fuel, spacecraft often make use of other planets they pass by to get a gravity assist to help them on their way. And that means that spacecraft frequently perform flybys of planets that are not their main focus of study.

Researchers don't waste any opportunity to learn about other planets though, so spacecraft often take as manyreadings as they can when passing by. For example, both the BepiColumbo spacecraft, on its way to study Mercury, and the Solar Orbiter spacecraft, designed to study the sun, have made recent flybys of Venus. Now, researchers are combining data from both of these missions to learn more about Venus and its magnetic field.

Read more